Rock sampling

ABSTRACT

AN APPARATUS FOR SAMPLING ROCK ANDOTHER BRITTLE MATERIALS AND FOR CONTROLLING RESULTANT PARTICLE SIZES. THE DEVICE INCLUDES GRINDING MEANS FOR CUTTING GROOVES IN THE ROCK SURFACE AND TO PROVIDE A GROUPING OF THIN, SHALLOW, PARALLEL RIDGES AND CUTTER MEANS TO REDUCE THESE RIDGES TO A POWDER SPECIMEN. COLLECTION MEANS IS PROVIDED FOR THE POWDER.

% WEIGHT PER CATEGORY Sept. 20,1971 P. BLUM 3,606,470

ROCK SAMPLING Original Filed Jan. 24, 1967 2 Sheets-Sheet 1 H9 F IG. IA

% WEIGHT PER CATEGORY 2O 0 3 PARTICLE SIZE PARTICLE SIZE F (IN MICRONS)(IN MICRONS) INVENTOR.

Sept. 20, 1'97] BLUM Y 3,606,470

' nocx SAMPLING Original Fil ed Jan. 24, 1967 Y z Sheets-Sheet 2 ROC KFIG. VIC

v 6 UL l I ATTORNEY 5 United States Patent Oflice 3,606,470 PatentedSept. 20, 11971 US. Cl. 299--67 4 Claims ABSTRACT OF THE DISCLOSURE Anapparatus for sampling rock and other brittle, materials and forcontrolling resultant particle sizes. The device includes grinding meansfor cutting grooves in the rock surface and to provide a grouping ofthin, shallow, parallel ridges and cutter means to reduce these ridgesto a powder specimen. Collection means is provided for the powder.

The present invention relates to rock grinding and particularly to thesampling of rock specimens with good size control. The inventiondescribed herein was made in the performance of work under a NASAcontract and is subject to the provisions of the National Aeronauticsand Space Act of 1958, Public Law 85-568 (72 Stat. 426; 42 U.S.C. 2451)as amended. A license has been granted to the United States Governmentfor practice of the invention and title to the invention and this patenthas been reserved to the assignee, subject to voidability by NASA.

The present invention relates to abrasive sampling of rock and otherbrittle materials which shatter during grinding due to a lack ofplasticity.

This application is a division of application Ser. No. 611,414, filedJan. 24, 1967, now abandoned.

There is a need in geological sampling for an apparatus which will grinda rock surface and give high yields in any desired particle size rangewithout recourse to classification or sieving techniques. An importantreason for avoiding classification or sieving techniques is that theyyield mineralogically unrepresentative powder specimens. The latterresults from the fragmentation of each mineral in a rock into a separatesize distribution.

It has been discovered that known grinding techniques do not affordadequate yield in coarse size ranges, e.g.

particle sizes between 75 and 150 microns, a range suitable for analysisby a petrographic microscope. Conventional grinding, e.g., of basalt,tends to produce particles with sizes predominantly below 44 microns.Variation of conventional grinding parameters such as wheel speed andgrit size, does little to increase the yield above this range or tochange the shape of the size distribution curve.

The present invention gives a two step treatment to rock or otherbrittle material. This consists of cutting a series 7 I FIG. 1 is aschematic sketch of an improved sampling apparatus;

FIG. 1A is a diagram showing a variation of the ridge cutter and FIGS.1B and 10 show other variations of the apparatus;

FIG. 2 is a bar graph showing size distribution of rock particlesobtained using prior art grinding techniques; and

FIG. 3 is a bar graph showing the improved distribution obtained in oneexample of use of the present invention.

Referring to FIG. 1 there is shown a rock 10 to be sampled, a toolcarriage 12 traversing in the path and direction indicated by the arrow14. Mounted on the carriage are a group of diamond surface cut-offwheels 18 and a milling cutter 20 with wedge s'haped teeth; The wheels18 and miller 20 are driven by a motor (not shown) mounted in thecarriage 12. The wheels 18 cut closely spaced parallel grooves 22 thusforming ridges 24. The milling cutter cuts the ridges down partially(but not fully) to produce a more controllable yield in terms ofparticle size. Only the milled powder is collected. A collection cup(not shown) is mounted on the apparatus for this purpose.

FIG. 1A shows a variation of the apparatus in which a single wheel withseveral parallel lands 114 is used instead of several grouped cut-01fwheels. It should be noted that here the rock sample has a narrowprofile. The profile should preferably be preground (by the wheel 11-8with abrasive on the flats 119 or a separate grinder) to the level 111to provide a common level for groove and ridge formation.

FIG. 1B shows a variation of the apparatus formed as a rock drill fortaking a sample in a pre-drilled hole. A wheel 118 (similar to the wheel118 of FIG. 1A) and a milling cutter are mounted on a common shaft 115.They are driven from support 114 for traversing on the same rotary pathand they are individually rotated by gears 130.

FIG. 10 shows another version of the apparatus on a pendulum mount withcutoff wheels 11 8 and a milling cutter 120 and collection boxes 226.The wheels 118 and 120 again travel the same path and same direction.The wheel drive transmission is not shown.

The pendulum continually swings around with the cutoff Wheel 118lowering the rock contour until a suitable level is obtained. Then thecollection means 226 collects a sample from the milling cutter 120 foruse in analytical processes.

FIG. 2 is a bar graph showing the highest yield of particles and inabout the 74149-m-icro-n range obtained by conventional grinding ofbasalt. (The particlesizes indicated on the abscissa between 0 andeo arethe'siev'e-sizes used.) The distribution shown'was obtained bytraversing the rock at 12 inches per minute, using a l'6-grit diamondwheel run at 44 0 revolutions per minute, and taking 'ofi 0.005 inch ofrock per traverse. 1

FIG. 3 shows the improved sample distribution obtained from the samerock using the method of. the present invention. Besides the improvementin immediate range of interest, which is shown shaded, there is asizable increase in the adjacent 149-250-micron range and a markedreduction in the under 44 micron range. Further peaking of thedistribution about the desired'74'*1'49 range can be obtained withfurther adjustment of ridge widths and heights as described below.The'results shown in FIG. 3 were obtained using the followingconditions: The previously described grooves were cut with a 60- milwidth and 35-mil depth producing intervening ridges of 15-mil width and35-mil height. The preformed surface was traversed by a flattooth'milling cutter rotating at4'40 revolutions per minute andtraversing at 3'0 inchespe'r minute. The milling cutter took- 0.008 inchofltheridges per traverse. I 7

The reasons for the size controlusing the present invention are thefollowing:' The production of grooves'removes considerable support fromthe remaining ridge material. As a result a reduction is'effected in theamount of mechanical crushing pressure required to'remove the ridgematerial. A reduction in the number of fine particles therefore results.Within limits, the thinner are the ridges, the fewer are the number offines that result. The ridge width is preferably about equal to thedesired particle size or in the range of the desired particle size. Theridge height is usually larger than the width and therefore the uppersize of the particles is primarily governed by, although not limited to,the height of the ridges.

Several variations can be made from the above-described embodiments. Itis therefore intended that the above disclosure shall be read asillustrative and not in a limiting sense.

What is claimed is:

1. An apparatus for geological rock sampling or the like comprising acombination thin wheel grinding means for cutting closely spaced groovesin the surface to create the elevated ridges and a milling cutter meansfor machining said elevated ridges simultaneously with a common toothcut of said multiple ridges and means for collecting the loose particlesproduced by said milling cut, the said grinding means and milling meansbeing supported on a common pendulum mounting structure to sweep along arock in a common path and common direction and spaced apart from eachother on said mounting structure, said collection means being mounted onsaid mounting structure and constructed and arranged to collect rockparticles removed by said milling means.

2. Apparatus for geological rock sampling comprising,

a frame means, a pair of spaced parallel rotary shafts mounted on saidframe means, a plurality of thin grinding wheels mounted in spaced apartrelation on one of said shafts for cutting a plurality of closely spacedgrooves in the surface of said rock and for creating elevated ridgesbetween said grooves, a toothed milling cutter mounted on the other ofsaid shafts and arranged to simultaneously reduce said plurality ofridges into a powder specimen, and collection means carried on saidframe for collecting said powder from said cutter.

3. The apparatus of claim 2 wherein said grinding and milling means areconstructed to sweep along the work in the same path.

4. The apparatus of claim 3 wherein said grinding and milling meanssweep along the work in the same direction.

References Cited UNITED STATES PATENTS 3,123,157 3/1964 Graham 175-583,374,034 3/1968 Conner 29986 1,496,522 6/ 1924 Canning. '1,5 80,l 4/1926 Niestradt 4 HAROLD D. WHITEHEAD, Primary Examiner US. Cl. X.R.

